Comparative studies on the spatial niche of zooplankton in the Liaohe estuary in spring and summer

We examined the seasonal spatial niche of zooplankton in the Liaohe estuary in August (summer) 2013 and May (spring) 2014.The niche breadth and niche overlap index of the dominant species were calculated using the Levins formula and the Petrailis index, respectively.The results showed that the niche breadth of the dominant species (class) ranged between 0.08 and 0.71.The niche breadth was further divided into broad niche (B_i>0.60), middle niche (B_i=0.30~0.60), and narrow niche (B_i < 0.30).We found that the species with broad niche were Paracalanus parvus, Acartia pacifica etc., those with middle niche consisted of A.bifilosa, P.crassirostris etc., and the species with narrow niche included Schmackeria poplesia, Oithona similis etc..The results of the CCA analysis showed that salinity and DO were the main environmental factors affecting the spatial distribution of zooplankton in spring and summer.